Protein Core Abstract High quality proteins are essential for the success of structural studies. The Protein Core will support any PCHPI- initiated projects and collaborators by producing milligram quantities of homogeneous recombinant viral protein, human cellular proteins and their complexes for structural studies. The Core will also carry out biophysical and bioanalytical characterization of proteins and protein complexes to support and validate structural studies. To that end the Core will work in an iterative fashion with the NMR Core to generate proteins suitable for structural studies and will provide protein and complexes to the X-ray Core and Cryo-EM Core for screening and structure determination. The Core will also communicate on a regular basis with the Interactions Discovery Core and HIV Virology Core, which together will provide information to the Protein Core on the discovery of novel target proteins and/or their validation, thus getting new complexes ready to enter the structure determination pipeline. Finally, the Core will support all Projects by making proteins for project goals.